The basis for dimension-five and dimension-six operators coincides
with the one in Refs. [1]}, [2]}. The two
dimension-five operators are the magnetic and electric dipole
operators,


Q(5)1 = e82 () F ,    Q(5)2 = e82 (i5) F ,

where \(F^{\mu \nu }\)  the electromagnetic field-strength tensor, and
\(\sigma ^{\mu \nu } = \tfrac{i}{2} [\gamma ^\mu , \gamma ^\nu ]\) . The four
dimension-six operators are formed from products of vector and
axial-vector currents,


Q(6)1,f = ()  (f f) ,    Q(6)2,f = (5)  (f f) ,
